Vacuum gold dredge



Feb. 18, 1941.

N. M I-IMAM VACUUM GOLD DREDGE 3 Sheets-Sheet 1 Filed Sept. 5, 1959 Feb. 18, 1941. N. M. OHMAN VACUUM GOLD DREDGE 3 Sheets-Sheet 2 r 7 1 a; 55 0 p .w d m m Feb-=18, 1941. OHMAN 2,231,941

VACUUM GOLD DREDGE I Filed SOP. 5, 1939 5 Sheets-Sheet 5 A7675 M ajlman w 5 e H'ITB 0 Patented Feb. 18, 1941 UNITED STATES PATENT OFFICE VACUUM GOLD DREDGE Application September 5, 1939, Serial No. 293,421

3 Claims.

This invention relates to gold dredges and more particularly to a dredge by means of which gold bearing material may be removed from the bottom of a river or other deep body of water.

One object of the invention is to provide a dredge consisting briefly of a caisson disposed vertically in the water with its lower end resting upon or partially embedded in the bottom of the river, and a pump cylinder suspended from hoisting means carried by a scow or the like, the cylinder being adapted to be lowered into the caisson to the bottom thereof and a piston operated to create a partial vacuum in the cylinder and thus draw earth and gravel into the cylinder where it is entrapped and carried upwardly with the cylinder for delivery into a sluice box on the scow.

Another object of the invention is to so form the cylinder and piston operating therein that they may both be carried by a cable of the hoisting mechanism on the scow, the piston being permitted to have movement relative to the cylinder so that when the cylinder is resting at the bottom of the caisson the piston may have movement to effect drawing of earth and gravel into the cylinder.

Another object ofthe invention is to provide the cylinder with an improved valve at its lower end so formed that an upper portion of the valve may have movement permitting earth and gravel to be drawn into the cylinder where it is retained until the cylinder has been withdrawn from the caisson and the valve released for movement to a dumping position.

A further object of the invention is to provide a piston which may move freely downwardly into the cylinder in which it operates but, when drawn upwardly, will create a vacuum condition in the cylinder under the piston for drawing earth and gravel into the cylinder, ports being formed in the walls of the cylinder to break the vacuum when the piston has been drawn upwardly to a position wherein further upward movement of the piston in the cylinder is prevented. It will thus be seen that after a load of dirt and gravel has been drawn into the cylinder the vacuum will be broken and the valve at the bottom of the cylinder will close.

A still further object of the invention is to provide a vacuum dredge which can accommodate itself to the depth of the water and also the depth of mud and gravel at the bottom of the river or other body of water.

And the invention has as a still further object to provide a dredge which may be shifted from place to place during dredging operations and thus all of the mud and gravel atpthe bottom of the body of water treated for recovering gold therefrom.

The invention is illustrated in the accompanying drawings, wherein:

Fig. 1 is a side elevation-showing a scow equipped with a dredge of the improved construction.

Fig. 2 is a front elevation thereof.

Fig. 3 is a sectional view on an enlarged scale, taken longitudinally of the vacuum' actuated dredge.

Fig. 4 is a top plan view of the piston which is slidable vertically in the cylinder of the dredge, on the line 4-4 of Fig. 3.

Fig. 5 is a transverse sectional view on the line 5-5 of Fig. 3.

Fig. 6 is a bottom plan view of the dredge.

The improved dredging apparatus constituting the subject matter of this invention is employed for recovering gold and other precious metals from the bottom of a body of water such as a river or lake, and includes a barge or float I, which may be of any dimensions desired. At one end of the barge is a derrick 2 having vertically disposed beams 3 connected at their upper ends by a cross head 4. The lower ends of the side beams are bolted to base beams 5 extending longitudinally of the barge and, in order to maintain the derrick in upright position, there have been provided braces 6 secured at their upper and lower ends to the side beams 3 and the base beams 5. Upper and lower side bars I and 8 are carried by the side beams and the braces, and upon referring to Fig. 1, it will be seen that the side bars and base beams project from the front end of the barge. An auxiliary support 9 extends from one side of the derrick to support forward portions of sluice boxes If] extending longitudinally of the barge and terminating at the rear end thereof, so that gold bearing material delivered into the sluice boxes through the trough Il may have gold and other precious metals washed from it as it moves through the sluice boxes, and water and tailings returned to the body of water. A hoist I 2 of conventional construction, including a drum I3, is mounted on the barge near the rear end thereof and upon the drum i3 is wound a cable M which extends forwardly at an upward incline and is trained about the guide pulley l5 and from this pulley extends downwardly with its front end secured to the extractor l6 by means of which gold bearing material is removed from the bed of the lake or river. The pulley I5 is rotatably mounted by a shaft ll projecting from opposite sides of the pulley and engaged in bearings l8 carried by the crosshead 4.

During use of the dredge, a caisson I9 is disposed vertically in the body of water with its lower portion extending to the bottom of the bed thereof and its upper portion projecting from the water a sufiicient distance to extend upwardly at the front end of the barge between protruding ends of the base beams 5 and the upper and lower side bars I and 8. Suitable anchoring means may be employed to hold the barge in close proximity to the caisson and permit the extractor to be lowered into the caisson and then drawn upwardly and out of the caisson after removing a portion of the river bed enclosed within the caisson. The material removed by the extractor is delivered into the trough I and from this trough passes into the sluice boxes lflwhere it is subjected to the action of flowing water and precious metals caught in the sluice boxes while the tailings are discharged from the rear ends of the sluice boxes.

The extractor I6 is illustrated in detail in Figs. 3 through 6 and referring to these figures, it will be seen that it has a cylindrical casing 23 which may be of any length desired and is of such diameter that it may easily move vertically through the caisson I9. This casing is open at its top and bottom and, at one side of its lower end carries elongated bearing members 2| with which a compound valve 22 is pivotally connected by a hinge pin 23 passing through the hinge ears 24 of the valve and through the bearing members 2 I. The valve has an annular body of a diameter adapting it to bear against the lower end of the cylindrical casing when closed and an upstanding annular wall 25 having a sloping upper edge against which rests an auxiliary valve disk or gate 26 which has hinge ears 29, and from an inspection of Fig. 3, it will be seen that the auxiliary valve disk or gate 26 may move inwardly to an open position independently of the main valve and also move outwardly with the main valve 22 when the main valve is released and allowedto swing downwardly to open position. A latch rod 30 which extends longitudinally of the casing 20, is provided for releasably holding the compound valve closed. This latch rod is rotatably mounted through the bearings 3i and, at its upper end, carries a handle 32 by means of which the rod is turned to move the bill 33 into and out of position to engage under the annular body of the compound valve and hold the same in raised or closed position against the lower end of the cylindrical casing 23. When the compound valve is in closed position and the cylinder is lowered through the caisson to a position in which it is embedded in the bed of the body of water, material may be drawn into the casing by suction which will swing the gate 26 upwardly to the position indicated by dotted lines in Fig. 3, and when the suction is broken, the weight of the material will close the gate. The material will thus be retained in the casing until the extractor is withdrawn from the caisson and moved to a position over the trough II, the latch rod then being turned to move its bill from under the valve and the entire valve will swing downwardly to the depending position indicated by dotted lines in Fig. 3, where it will be out of the way and permit the contents of the casing to drop through the open lower end-thereof. If it is found more convenient to do so, a short rod 34 may be engaged in an opening 35 formed near the lower end of the latch rod and turning motion imparted to the latch rod.

When the casing 2 is lowered through the caisson into the bed of the lake or river, gold bearing material is to be sucked into the casing through the lower end thereof. In order to do so, there has been provided a piston 36 formed of upper, lower and intermediate sections or blocks 3'1, 33 and 39 which are secured in a stack by a bolt 40 having an eye 4| at its upper end. A shackle 42 is pivotally carried by the eye at the upper end of the bolt and through this shackle is passed the front end of the cable 14, a stop- 43 being carried by the cable to hold the cable in engagement with the shackle and cause the piston to be drawn upwardly when the cable is wound upon the drum of the hoist l2. The cable also passes through the eye 44 of a yoke 45 straddling the upper end of the casing and about the cable is disposed a spring 46 serving as a bumper to absorb shocks when the cable is wound upon the drum andpermitting the extractor to be withdrawn from the caisson without undue strain upon the cable. Openings 4'! are formed through the piston at opposite sides of the bolt 40 to permit the piston to move easily downwardly through the casing to a position close to the closed compound valve 22 and, in order to close these openings, during upward movement of the piston, there have been provided gate valves 43 which are hinged, as shown at 49, for movement from a closed position to a raised or open position. It will thus be seen that after the casing has been lowered through the caisson to a position in which it is embedded in the bed of the body of water, the piston may move downwardly to the bottom of the casing and water will pass upwardly through the openings 41. The piston may then be drawn upwardly and during this movement, the gate valves 48 will be closed and suction created under the piston to raise the gate 26 and draw gold bearing material into the casing. As the piston is drawn upwardly, it passes the openings 50 formed in the casing and air will enter the casing under the piston to break the suction and the gate valve 26 will then close and trap the gold bearing material in the casing. The piston continues its upward movement until the spring 45 engages the eye 44 of the yoke 45 and the entire extractor will then be drawn upwardly through the caisson and through the upper end thereof to a position in which it may be disposed over the trough H and the latch rod then turned to release the compound valve 22 and allow this valve to swing downwardly to the lowered or opened position and the gold bearing material will drop from the casing 20 into the trough. The valve 22 will then be closed and secured by returning the latch rod to the position shown in Fig. 3 and the extractor is ready to be again lowered into the caisson for another load of gold bearing material. It will thus be seen that with this apparatus, gold bearing material may be removed from the bottom of a lake or river and the gold or other precious metals therein recovered, the tailings being returned to the water by flowing from the rear ends of the sluice boxes 10.

Having thus described the invention, what is claimed is:

1. In mining apparatus, an extractor comprising a casing open at its upper and lower ends, a piston slidable longitudinally in said casing, a compound valve at. the lower end of said casing having a ring-like body pivoted to said casing at one side thereof for swinging movement from a lowered position to a raised position against the lower end of the casing, an upstanding annular wall for the valve body extending into the casing when the valve body is in its raised position, the annular wall of the valve body being tapered upwardly to provide clearance as the valve body is swung upwardly into the casing, a gate pivoted at one side to the annular wall of the valve body for vertical swinging movement from a raised position to a lowered position in closing engagement with the upper edge of the annular wall of the valve body, and means for releasably holding the valve body in its raised position against the lower end of the casing.

2. In n'lining apparatus, an extractor comprising a cylindrical casing open at its upper and lower ends, a compound valve at the lower end of said casing having an annular body movable from a lowered open position to a raised position in closing engagement with the lower end of the casing, a gate pivoted to the valve body and movable upwardly in the casing from a closed position to an opened position, a rod extending longitudinally of the casing and rotatably mounted, said rod having a bill at its lower end for engaging under the valve and releasably holding said valve in closing engagement with the lower end of the casing, a piston in said casing slidable longitudinally therein, means for connecting said piston with hoisting means, said piston being formed with longitudinally extending passages, and closures for the passages movable upwardly out of closing relation to said passages.

3. In mining apparatus, an extractor comprising a cylindrical casing open at its upper and lower ends, a compound valve at the lower end of said casing movable from a lowered opened position to a raised position in closing engagement with the lower end of the casing, a gate for said valve movable inwardly of the casing from a closed position to open position, a latch for releasably holding said valve in its closing engagement with the lower end of the casing consisting of a rod extending longitudinally of the casing externally thereof and rotatably mounted, said rod having a bill at its lower end and a handle for turning the rod and moving the bill into and out of position to engage under and support the valve in its closed position, a piston in said casing slidable longitudinally therein, a shackle carried by said piston for connecting the piston with a hoisting cable, said piston being formed with longitudinally extending passages, and gates pivoted to the upper end of said piston and movable upwardly to open position from closed position at rest upon the upper end of the piston.

NELS M. OHMAN. 

